George Osborne will have been mightily relieved to see this morning's upbeat survey from the critical services sector. The strong reading of 55.7 fits neatly into the story he and his colleagues have been telling and re-telling at every available opportunity – that recovery from recession is always "choppy," December's snow was bound to put the chill on the economy, and we'll soon be back on course.

Manufacturing is expanding at a rapid clip, according to the January PMI. If services has also bounced back strongly from its bleak midwinter, the recovery may be back on track, and the Treasury can write off the dismal final quarter of 2010 – when the economy contracted by 0.5% – as an icy aberration.

That may be too easy. Some of the activity lost in December was bound to be made up in January. But analysts were quick to point today out that, looked at over three months, the services sector is still at its weakest since Britain was in the depths of recession, in summer 2009.

Vicky Redwood, of Capital Economics, said a weighted average of the PMI surveys for manufacturing and services pointed to modest quarterly growth of just 0.2-0.3% – that's certainly a recovery, but a sickly one at best.

So with house prices falling once again, hundreds of thousands of public sector job losses starting to bite, and most other major economies still stuck in the doldrums, constraining manufacturers' hopes of an export surge, there's a different story we could tell about this morning's survey. Instead of pointing to what Bank of England hawk Andrew Sentance has called the UK's "bouncebackability," it confirms the fragile state of the economy, even before the real pain of spending cuts is felt, and underlines the risk that the government has clobbered the recovery.

The challenge for the wonks at No 11 – and the Bank's policymakers, who meet next week – is that we won't know which of these tales is true for some time – and there's plenty of scope right now for devastating policy mistakes.

The hawks on the Bank's monetary policy committee are already flexing their wing-tips, itching to get interest rates rising, and they will take this morning's survey as fresh evidence that the economy is on track. But long before the credit crunch was ever heard of, back in 2005, Mervyn King was warning that, "the true meaning of the Christmas story will not be revealed until Easter – or possibly much later". He is likely to urge his colleagues next week to wait and see – and they would be wise to listen.

For the chancellor, meanwhile, this morning's news may be welcome, but he should not use it as an excuse to write off the shocking fourth quarter. Instead, he should heed the IFS's call yesterday that he draw up – and tell us about – a "Plan B" in case the recovery is not just "choppy" but, because of his aggressive policies, sunk without trace.